To assess the originality and integrity of multimedia data a variety of authentication techniques have been proposed. Among the proposed authentication techniques, digital watermarking and digital signature are two basic categories that may be classified as active detection techniques. Watermarking schemes may meet certain requirements such as fidelity that may pose more significant challenges for video media. For example, in Motion Picture Experts Group (MPEG) video, dependency among frames may cause distortion resulting from a digital watermark in an intra-coded I frame to propagate through associated predictive coded frames (P frame) and bi-directionally predictive coded frames (B frames). Furthermore, not all MPEG video frames are typically watermarked.
Because of the large quantities of data involved in video, tampered video sequences are typically encoded and stored in a compressed format, and thus tampered video will usually have been subjected to compression twice. Determining whether video has been tampered may be useful. For example, in criminal investigations, video may be considered as valid evidence if it may be shown to be an original recording of a crime scene. The detection of video double compression may play a role in originality authentication in such a scenario.